Matthew O'Reilly Dease of Dunleer, county Louth, was Member of Parliament for that county from 1868 to 1874. He was son of Richard Dease, a medical doctor and his second wife, Anna Maria O'Reilly of Knock Abbey, county Louth. At the time of Griffith's Valuation Matthew O'Reilly Dease held land in the parish of Ballynamona, barony of Smallcounty, county Limerick. In 1876 he owned land in counties Louth, Cavan, Limerick (446 acres), Meath and Dublin but his largest acreage was in county Mayo where he owned an estate of 2366 acres. He sold his county Mayo estate to the Congested Districts' Board on 2 Dec 1898.
National Archives of Ireland:
Map of property transferred to Matthew O'Reilly Dease MP by Landed Estates' Court. Small Accs. Index 19, LEC 130